1. (Field of the Invention)
This invention relates to a motion conversion mechanism comprising a threaded shaft and a nut for converting rotation into a translational motion.
2. (Prior Art)
As a motion conversion mechanism for converting rotation into a translational motion, there is one comprising a threaded shaft and a nut screwed thereon. Herefore, for permitting smoother motion of the nut in such a motion translation mechanism, use has made of various ball screw nuts featuring low frictional resistance.
When the nut of the motion conversion mechanism is a ball screw nut, it is possible to obtain smooth motion of the nut. In the aspect of the manufacture, however, high precision is required for the groove, in which the ball is meshed. Further, lubricant is required. Therefore, the mechanism is not suited for use in places where the foodstuff and chemicals are dealt with and oil is detested. Further, its use in water is not suited because of the generation of rust.
An object of the invention is to provide a motion conversion mechanism which can solve the above problems.